Method for adjusting a grille shutter opening

Field

The present description relates generally to methods and systems for controlling a vehicle engine.

Background/summary

Vehicles operating with combustion cylinders may be configured to inject fuel directly into the fuel chamber. In such a configuration, fuel injected into the cylinder may impinge on the cylinder bore walls and accumulate in the oil pan in the crankcase. If the rate of accumulation exceeds the rate of evaporation of fuel from the crankcase (e.g., via a positive crankcase ventilation (PCV) system), the fuel may dilute oil in the oil pan of the crankcase. Fuel in oil dilution may degrade oil quality, cause fuel odors in the engine oil, and degrade oxygen intake sensors via evaporation.

Other attempts to address fuel in oil dilution include selectively providing coolant to the engine based on fuel in oil dilution. One example approach is shown by Takahashi et al. in U.S. Pat. No. 7,493,883. Therein, a cooling jacket surrounding the crankcase of the engine is included in the coolant circuit when oil in fuel dilution is below a threshold level, and is bypassed in the coolant circuit when oil in fuel dilution is above a threshold level to raise the temperature of the crankcase and provide greater fuel vaporization.

However, the inventors herein have recognized potential issues with such systems. As one example, fuel economy may be degraded in instances where the engine is at a high temperature due to fuel in oil dilution but an acceleration event is commanded. As a further example, coolant may only be fully provided to the engine crankcase or absent from the cooling jacket, and not partially provided to the cooling jacket, providing a less than desired level of temperature control of the engine crankcase.

In one example, the issues described above may be addressed by selectively adjusting a grille shutter opening responsive to fuel in oil dilution. The adjusting of the grille shutter responsive to fuel in oil dilution may be in coordination with adjusting the grille shutter to control coolant temperature and aerodynamics for maintenance of engine cooling performance and improved fuel economy, respectively.

As one example, in response to a fuel in oil dilution level above an upper threshold, a grille shutter may be adjusted from a first mid-point position further from the fully closed position to a second mid-point position closer to the fully closed position. Temperatures within the engine compartment may then increase, and more fuel may vaporize out of the oil in the crankcase. In response to a fuel in oil dilution level returning to below the upper threshold, a grille shutter may be adjusted from the second mid-point position to a different position based on one or more of coolant temperature, charge air cooler temperature, and various vehicle motion parameters. In this way, fuel in oil dilution may be improved while still enabling accurate control of coolant temperature and improving fuel economy.

It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

Brief description of the drawings

FIG. 1 depicts an engine system with adjustable grille shutters, configured with a turbocharger, direct fuel injectors for injecting gasoline, positive crankcase ventilation, exhaust gas recirculation, and fuel vapor purge.

FIG. 2 depicts a fuel system configured for direct fuel injection.

FIG. 3 depicts a flowchart for adjusting a grille shutter opening based on ECT, acceleration/deceleration, additional engine operating conditions including CAC temperature, and oil dilution.

FIG. 4 depicts a flowchart for estimating an amount of oil dilution based on one of a PCV fuel compensation strategy and an oil dilution mode.

FIG. 5 depicts a flowchart for a PCV fuel compensation strategy used to estimate an amount of oil dilution based on intake air oxygen sensor measurements.

FIG. 6 depicts a flowchart for selectively adjusting a commanded grille shutter position based on each of ECT and oil dilution.

FIG. 7 depicts a flowchart for adjusting a commanded grille shutter position via a second method.

FIG. 8 depicts a prophetic sequence of adjusting a grille shutter opening based on each of ECT and acceleration/deceleration, and selectively adjusting the opening further based on oil dilution.

Detailed description

The following description relates to systems and methods for adjusting a grille shutter opening based on fuel in oil dilution. FIGS. 1 and 2 depict an example engine system with which these methods may be executed. FIG. 3 provides a high-order flowchart for adjusting the grille shutters based on several engine operating conditions including ECT, acceleration/deceleration, and oil dilution. Oil dilution may be estimated via the routine provided at FIG. 4 . One method of estimating the oil dilution may include estimating a dilution amount based on the hydrocarbon content of the crankcase gases delivered to an intake air oxygen sensor, as depicted at FIG. 5 . FIGS. 6-7 provide two methods for adjusting a commanded grille shutter position based on an estimated oil dilution amount, the commanded grille shutter position determined based on other engine operating conditions. FIG. 8 shows a graphical example of adjusting grille shutters based on engine coolant temperature, acceleration/deceleration, and oil dilution amount.

FIG. 1 shows an example embodiment of a grille shutter system 110 and an engine system 100 , in a motor vehicle 102 , illustrated schematically. Engine system 100 may be included in a vehicle such as a road vehicle, among other types of vehicles. While the example applications of engine system 100 will be described with reference to a vehicle, it should be appreciated that various types of engines and vehicle propulsion systems may be used, including passenger cars, trucks, etc.

An example configuration of a multi-cylinder engine is generally depicted at 111 , which may be included in a propulsion system of an automobile. Engine 111 may be controlled at least partially by a control system 160 of the vehicle including controller 166 and by input from a vehicle operator 132 via an input device 130 . In this example, input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP (not shown).

In the depicted embodiment, engine 111 is a boosted engine coupled to a turbocharger including a compressor 50 driven by a turbine 62 . Further, engine 111 is configured to inject fuel from fuel tank 128 directly into combustion chamber 34 via direct fuel injector 220 . Thus, in examples where the fuel in fuel tank 128 is gasoline, engine 111 is a gasoline turbocharged direct injection engine. Specifically, fresh air is introduced along intake passage 12 into engine 111 via air filter 54 and flows to compressor 50 . The compressor may be a suitable intake-air compressor, such as a motor-driven or driveshaft driven supercharger compressor. In the engine system 100 , the compressor is shown as a turbocharger compressor mechanically coupled to turbine 62 via a shaft (not shown), the turbine 62 driven by expanding engine exhaust. In one embodiment, the compressor and turbine may be coupled within a twin scroll turbocharger. In another embodiment, the turbocharger may be a variable geometry turbocharger (VGT), where turbine geometry is actively varied as a function of engine speed and other operating conditions. In yet another embodiment, the turbine and compressor may be included as a supercharger.

Engine 111 may include a lower portion of the engine block, indicated generally at 26 , which may include a crankcase 28 encasing a crankshaft 30 . Crankcase 28 may include an oil sump 32 , otherwise referred to as an oil well, holding engine lubricant (e.g., oil) positioned below the crankshaft 30 . During some conditions, fuel may enter crankcase 28 via engine cylinders, for example. An oil fill port 29 may be disposed in crankcase 28 so that oil may be supplied to oil sump 32 . Oil fill port 29 may include an oil cap 33 to seal oil port 29 when the engine is in operation. A dip stick tube 37 may also be disposed in crankcase 28 and may include a dipstick 35 for measuring a level of oil in oil sump 32 . In addition, crankcase 28 may include a plurality of other orifices for servicing components in crankcase 28 . These orifices in crankcase 28 may be maintained closed during engine operation so that a crankcase ventilation system (described below) may operate during engine operation. Further, crankcase 28 may include an air-to-fuel ratio sensor for sensing an air-to-fuel ratio in a positive crankcase ventilation (PCV) system 16 .

The upper portion of engine block 26 may include a combustion chamber (e.g., cylinder) 34 . The combustion chamber 34 may include combustion chamber walls 36 with piston 38 positioned therein. Piston 38 may be coupled to crankshaft 30 so that reciprocating motion of the piston is translated into rotational motion of the crankshaft. Combustion chamber 34 may receive fuel from fuel injectors (e.g., direct fuel injector 220 ) and intake air from intake manifold 42 which is positioned downstream of throttle 44 . The engine block 26 may also include an engine coolant temperature (ECT) sensor 46 input into a controller 166 (described in more detail below herein).

Motor vehicle 102 further includes a grille system 110 including a grille 112 providing an opening (e.g., a grille opening, a bumper opening, etc.) for receiving ambient air flow 116 through or near the front end of the vehicle and into the engine compartment. For this reason, ambient air flow 116 is herein also referred to as an engine front-end airflow. Ambient air flow 116 may then be utilized by radiator 80 , engine cooling fan 92 , and a low-temperature radiator (not shown) to keep the engine and/or transmission cool. The engine cooling fan 92 may be adjusted to further increase or decrease the air flow to the engine components.

Grille shutters 114 may be selectively adjusted to affect the amount of ambient air flow 116 that is passed through grille 112 . As used herein, adjusting grille shutters 114 includes adjusting the size of a grille shutter opening resultant from the position or degree of inclination of grille shutters 114 . The position or degree of inclination of grille shutters 114 may be estimated based on feedback from grille shutter position sensor 118 . A grille shutter opening may be a percent of openness from 0-100%, where 0% is completely closed and 100% is completely open. For example, grille shutters 114 may be adjusted to be completely shut (0% grille shutter opening) and prevent the flow of air through grille 112 , or may be adjusted to be completely open (100% grille shutter opening) and allow an unrestricted flow of air through grille 112 . Furthermore, grille shutters 114 may be adjusted to any one of an infinite number of positions between completely closed and fully open (corresponding to a grille shutter opening between 0% and 100%). In this way, an engine front-end airflow (e.g., ambient airflow 116 ) may be adjusted by adjusting a grille shutter position.

While this example refers to operation of grille shutters, various other devices may also be used that variably restrict airflow entering the engine compartment, such as a variable wing or spoiler, as one example, that can be adjusted to various angles including mid-point angles between maximum and minimum angle positions.

As used herein, the terms “open grille shutter position” and “open position” refer to a grille shutter position that is more than half open, or put another way, a grille shutter opening that is greater than 50%. Similarly, “closed grille shutter position” and “closed position” refer to a grille shutter position that is less than half open, or put another way a grille shutter opening that is less than. Further, a “fully open” or “completely open” position refers to approximately a 95%-100% grille shutter opening, while a “fully closed” or “completely closed” position refers to approximately a 0-5% grille shutter opening. As used herein, a mid-point opening refers to grille shutter opening between fully closed (0% open) and fully open (100% open).

When grille shutters 114 are completely shut, hot air within the engine compartment may remain in the engine compartment and contribute to an increase in the ambient temperature within the engine compartment. When grill shutters 114 are completely open, ambient air flow 116 may serve to circulate hot air out of the engine compartment, thereby reducing the ambient temperature within the engine compartment. Adjusting grille shutters 114 to a degree of inclination between completely closed and completely open may result an ambient airflow 116 and an ambient temperature greater than those that arise when grille shutters 114 are completely open. In this way, the temperature within engine compartment 102 may be at least partly controlled by adjusting the degree of inclination of the grille shutters. Furthermore, as described in further detail below, a grille shutter opening may be adjusted in response to various engine operating conditions such as engine speed and load, vehicle speed, pedal position, conditions of the CAC (CAC temperature, pressure, and efficiency), engine temperatures, ECT, fuel in oil dilution level, intake air oxygen content, feedback grille shutter position, etc., in order to improve one or more of fuel economy, engine performance, and oil dilution levels. For example the aerodynamics of vehicle 102 may be improved with a fully closed grille shutter 114 via a streamlining of the front end of the vehicle, and therefore during some conditions a fully closed grille shutter may improve fuel economy.

In one example, an engine system may detect fuel in oil dilution in the crankcase (e.g., via operation in combination with routine 400 at FIG. 4 , having corresponding instructions stored in the memory of controller 166 ), and in response may adjust a grille shutter 114 to a more closed position. In one example, the grille shutter opening may be adjusted to 0%. In another example, if the grille shutter opening was at 100% or at a mid-point opening, the grille shutter opening may be adjusted to position closer to 0% but not fully closed. In this way, ambient temperature may be raised in the engine compartment and vaporization of fuel within the crankcase oil may be increased.

In another example, an engine controller may anticipate an acceleration event (e.g., from operator 132 via input device 130 ) in the near future. In response to an anticipated acceleration event, the engine controller may adjust the grille shutter opening to 100%. In another example, if the grille shutter was at 0% or at an intermediate position, the grille shutter opening may be adjusted to a position closer to 100% but not fully opening. In this way, ambient temperature may be decreased in the engine compartment and overheating of the engine via the anticipated acceleration may be avoided, thereby improving engine efficiency. Further examples of adjusting grille shutter responsive to various engine conditions are discussed with references to FIGS. 3, 6-8 .

Air may enter the engine compartment via grille system 110 and be introduced to fresh air intake passage 12 . Fresh air intake passage 12 may include air filter 54 , and may further include a barometric pressure sensor (BP sensor) 53 , upstream of air filter 54 , for providing an estimate of barometric pressure (BP), as well as a compressor inlet pressure (CIP) sensor 58 may be coupled in intake passage 12 downstream of air filter 54 and upstream of compressor 50 to provide an estimate of the compressor inlet pressure (CIP). These sensors may be in electronic communication with controller 166 .

Engine intake may be in fluid communication with a positive crankcase ventilation (PCV) system 16 , a fuel vapor purge (FVP) system 17 and an exhaust gas recirculation (EGR) system 18 . Specifically, crankcase ventilation tube 74 of PCV system 16 may be coupled to intake passage 12 upstream of compressor 50 via a first end 101 and may be further coupled to crankcase 28 via an oil separator 81 and a second end 103 . Crankcase ventilation tube 74 may couple crankcase 28 to intake passage 12 downstream of air filter 54 and upstream of compressor 50 . During boosted conditions, gases in the crankcase may be vented from the crankcase through tube 74 in a controlled manner. In some examples, the gases delivered from crankcase 28 to intake air passage 12 via tube 74 and first end 101 may include vaporized fuel that had previously escaped from combustion chamber 34 and diluted into the oil of oil sump 32 . For this reason, crankcase ventilation tube 74 may herein also be referred to as a push-side conduit or a push-side pipe, and first end 101 may be referred to herein as a push-side port. Further, gases traveling in such a manner may be referred to herein as PCV push-side flow, and push-side PCV flow is said to be “active” or “present” when gases are flowing from crankcase 28 to intake air passage 12 via tube push-side conduit 74 and push-side port 101 . However, during non-boosted conditions, a vacuum created in intake manifold 42 may induce air from intake passage 12 to flow into crankcase 28 via conduit 74 .

Conduit 76 of PCV system 16 may deliver gases from crankcase 28 to intake manifold 42 , downstream of each of compressor 50 , IAO2 sensor 88 , and throttle 44 . During boosted conditions, PCV valve 78 may prevent crankcase gases from flowing through conduit 76 and into intake manifold 42 . However during non-boosted conditions, a vacuum may be created in intake manifold, and the vacuum may pull gases from crankcase 28 through conduit 76 and into intake manifold 42 via PCV valve 78 and port 77 . For this reason, conduit 76 may also be referred to herein as a pull-side pipe or a pull-side conduit, while port 77 may be referred to herein as a pull-side port. Further, gases traveling in such a manner may be referred to herein as PCV pull-side flow, and pull-side PCV flow is said to be “active” or “present” when gases are flowing from crankcase 28 to intake manifold 42 via tube pull-side conduit 76 and pull-side port 77 . In some examples, the gases delivered from crankcase 28 to intake manifold 42 via pull-side conduit 76 may include vaporized fuel that had previously escaped from combustion chamber 34 and diluted into the oil of oil sump 32 .

Fuel vapor purge system 17 may be fluidly connected to intake air passage 12 upstream of compressor 50 via duct 152 and to intake manifold 42 downstream of throttle 44 via duct 148 , and may be configured to deliver fuel vapors from fuel tank 128 to each of intake passage 12 and intake manifold 42 . In one example, when FVP is enabled, fuel vapors may be delivered to the intake system via duct 152 during boosted conditions, and via duct 148 during non-boosted conditions. Passage 51 of EGR system 18 may direct exhaust flow downstream of turbine 62 in exhaust passage 60 back to intake passage 12 , downstream of air filter 54 and upstream of compressor 50 .

Intake manifold 42 may include pressure sensor 86 for measuring an intake manifold pressure (MAP). Intake manifold 42 further includes intake air oxygen (IAO2) sensor 88 for measuring an oxygen content of air entering cylinder 34 . IAO2 sensor 88 may be one of a linear oxygen sensor universal or wide-range oxygen sensor, a two-state oxygen sensor, and a heated oxygen sensor. IAO2 sensor 88 may be positioned downstream of each of the fluid connections to the FVP and EGR systems 17 and 18 , and upstream of intake valve 31 such that oxygen content is measured after all effluents have been introduced to the intake stream. Further, IAO2 sensor may be positioned downstream of push-side conduit 74 but upstream of pull-side conduit 76 . During some conditions, when EGR and fuel vapor purge are inactive and push-side PCV flow is active (e.g., during boosted conditions), measurements from IAO2 sensor 88 may be used to determine a hydrocarbon (HC) concentration of gases from crankcase 28 . During other conditions, measurements from IAO2 sensor 88 may be used to determine an amount of recirculated exhaust gas to introduce to intake manifold 42 via EGR system 18 .

As shown in FIG. 1 , compressor 50 is coupled to charge air cooler (CAC) 52 . In an alternate embodiment, the throttle 44 may be coupled to the engine intake manifold 42 , downstream of the CAC 52 . From the compressor, the hot compressed air charge enters the inlet of the CAC 52 , cools as it travels through the CAC, passes through the throttle valve 44 , and then exits toward the intake manifold 42 . In the embodiment shown in FIG. 1 , the CAC 52 is a water-to-air heat exchanger. As such, CAC 52 comprises a series of coolant tubes which water or coolant may flow through to cool the charge air passing over the outside of the coolant tubes. The coolant tubes of CAC 52 may be connected to a low-temperature radiator circuit (not shown). The low-temperature radiator circuit may include a low-temperature radiator, coolant tubing, and a coolant pump (not shown). The low-temperature radiator may cool warmed coolant flowing from the CAC 52 . As such, the coolant pump may pump cooled coolant from the low-temperature radiator, through the coolant tubing, and to the CAC 52 . Coolant then flows through the coolant tubes of the CAC 52 , thereby cooling warmer charge air passing through the CAC 52 . As the coolant travels through the CAC, the temperature of the coolant may increase. Warmed coolant may then travel from the CAC 52 back to the low-temperature radiator to be cooled again.

A throttle 44 may be disposed in intake passage 12 to control the airflow entering intake manifold 42 and may be preceded upstream by compressor 50 followed by charge air cooler 52 , for example. Compressor 50 may compress the intake air to engine 111 , thereby boosting intake air pressure and density providing boosted engine conditions (e.g., manifold air pressure>barometric pressure), for example during increased engine loads. An air filter 54 may be positioned upstream compressor 50 and may filter fresh air entering intake passage 12 . In the depicted example, throttle 44 is positioned upstream of PCV pull-side port 77 and FVP duct 148 , and downstream of each of PCV push-side port 101 , EGR passage 51 , FVP duct 152 , compressor 50 , CAC 52 , and IAO2 sensor 88 .

Intake manifold 42 is coupled to a series of combustion chambers 34 through a series of intake valves 31 . It will be understood that although as depicted in FIG. 1 , intake manifold 42 comprises only one section delivering effluent to only one combustion chamber 34 , engine 111 may comprise multiple combustion chambers 34 , only one of which is shown, and intake manifold 42 may comprise a plurality of intake manifold sections to deliver effluent from a common intake passage to the plurality of combustion chambers 34 . The combustion chambers are further coupled to exhaust manifold 60 via a series of exhaust valves 39 . In the depicted embodiment, a single exhaust manifold 60 is shown. However, in other embodiments, exhaust manifold 60 may include a plurality of exhaust manifold sections. Configurations having a plurality of exhaust manifold section may enable effluent from different combustion chambers to be directed to different locations in the engine system. Universal Exhaust Gas Oxygen (UEGO) sensor 64 is shown coupled to exhaust manifold 60 upstream of turbine 62 . Alternatively, a two-state exhaust gas oxygen sensor may be substituted for UEGO sensor 64 .

In the example of FIG. 1 , a positive crankcase ventilation system (PCV) 16 is coupled to the engine fresh air intake 12 so that gases in the crankcase 28 may be vented in a controlled manner. During normal engine operation, gases in the combustion chamber 34 may escape past the piston. These blow-by gases may include unburned fuel, combustion products, and air. Blow-by gases can dilute and contaminate oil, causing corrosion to engine components and contributing to sludge build-up, reducing the protective and lubricating properties of the oil. At higher engine speeds, blow-by gases can increase crankcase pressure such that oil leakage may occur from sealed engine surfaces. The PCV system 16 may help to vent and remove blow-by gases from the engine crankcase in a controlled manner in order to mitigate these harmful effects of blow-by gases and may combine them with an engine intake stream so that they may be combusted within the engine. By redirecting blow-by gases to the engine intake, the PCV system 16 further aids in reducing engine emissions by precluding venting of blow-by gases to the atmosphere.

In one example, PCV system 16 may help to remove fuel in oil dilution of oil in engine crankcase 28 . Specifically, when engine temperatures are above a threshold temperature, fuel diluted in crankcase oil may vaporize out of solution and instead may partially compose the blow-by gas ventilated by PCV system. The amount of vaporized fuel may increase with increased temperature. Thus, by increasing engine temperatures, for example by closing grille shutters 114 of engine system 100 , more vaporized fuel may compose the blow-by gas of crankcase 28 and be ventilated out of crankcase, thereby reducing a fuel in oil dilution of oil in the crankcase. In this way, oil dilution may be improved during conditions where the PCV system is active.

The PCV system 16 includes a PCV valve 78 fluidly coupled to engine crankcase 28 . As an example, the PCV valve 78 may be coupled to a valve cover in the engine, which may allow for the PCV system to draw blow-by gases from the engine while reducing the entrainment of oil from the crankcase. The PCV valve 78 may also be fluidly coupled to the engine intake manifold 42 . The PCV valve gas flow rate may vary with engine conditions such as engine speed and load, and the PCV valve 78 may be calibrated for a particular engine application wherein the PCV valve gas flow rate may be adjusted as operating conditions change. As an example, when the engine is off, the PCV valve may be closed and no gases may flow through the PCV valve 78 . When the engine speed is idling or low, or during deceleration when the intake manifold vacuum is relatively high, the PCV valve 78 may open slightly, allowing for restricted PCV valve gas flow rates. At engine speeds or loads higher than idling, intake manifold vacuum may lower, and the PCV valve 78 may allow for higher PCV valve gas flow rates. PCV valve 78 may include a conventional PCV valve or a push-pull type PCV valve. As one example, PCV valve 78 may be a check valve.

In some embodiments, crankcase ventilation tube 74 may include a pressure sensor 61 coupled therein. Pressure sensor 61 may be an absolute pressure sensor or a gauge sensor. One or more additional pressure and/or flow sensors may be coupled to the PCV system 16 at alternate locations. In one example, pressure sensor 61 may be configured as a gauge sensor, and barometric pressure sensor 58 , coupled to intake passage 12 upstream of air filter 54 , may be used in conjunction with pressure sensor 61 . In some embodiments, a compressor inlet pressure (CIP) sensor 58 may be coupled in intake passage 12 downstream of air filter 54 and upstream of compressor 50 to provide an estimate of the compressor inlet pressure (CIP).

While the engine is running under light load and moderate throttle opening, such as during non-boosted conditions, the intake manifold air pressure may be less than crankcase air pressure. The lower pressure of the intake manifold 42 draws fresh air towards it, pulling air from the push-side conduit 74 through the crankcase (where it dilutes and mixes with combustion gases), out of the crankcase via the pull-side conduit 76 through the PCV valve 78 , and into the intake manifold 42 . However, during other conditions, such as heavy load or under boosted conditions, the intake manifold air pressure may be greater than crankcase air pressure. As such, intake air may travel through the PCV conduit 76 and into the crankcase 28 .

Specifically, during non-boosted conditions (when intake manifold pressure (MAP) is less than barometric pressure (BP)), the PCV system 16 draws air into crankcase 28 via a breather or crankcase ventilation (vent) tube 74 . A first end 101 of crankcase ventilation tube 74 may be mechanically coupled, or connected, to fresh air intake 12 upstream of compressor 50 . In some examples, the first end 101 of crankcase ventilation tube 74 may be coupled to fresh air intake 12 downstream of air filter 54 (as shown). In other examples, the crankcase ventilation tube may be coupled to fresh air intake 12 upstream of air filter 54 . In yet another example, the crankcase ventilation tube may be coupled to air filter 54 . A second end 102 , opposite first end 101 , of crankcase ventilation tube 74 may be mechanically coupled, or connected, to crankcase 28 via an oil separator 81 .

Still during non-boosted conditions, PCV system 16 may vent air out of crankcase 28 and into intake manifold 42 via pull-flow conduit 76 which, in some examples, may include a one-way PCV valve 78 to provide continual evacuation of gases from inside the crankcase 28 before connecting to the intake manifold 42 . In one embodiment, the PCV valve 78 may vary its flow restriction in response to the pressure drop across it (or flow rate through it). However, in other examples conduit 76 may not include a one-way PCV valve. In still other examples, the PCV valve may be an electronically controlled valve that is controlled by controller 166 . It will be appreciated that, as used herein, pull-side PCV flow refers to the flow of gases through conduit 76 and pull-side port 77 from the crankcase to the intake manifold 42 . As an example, the pull-side PCV flow may be determined from the fuel (e.g., gaseous fuel) injection rate, the air/fuel ratio in the engine intake, and the exhaust oxygen content via exhaust gas sensor 64 , using known methods.

As used herein, PCV backflow refers to the flow of gases through pull-side conduit 76 from the intake manifold 42 to the crankcase 28 . PCV backflow may occur when intake manifold pressure is higher than crankcase pressure (e.g., during boosted engine operation). In some examples (such as the depicted example), PCV system 16 may be equipped with a check valve for preventing PCV backflow. It will be appreciated that while the depicted example shows PCV valve 78 as a passive valve, this is not meant to be limiting, and in alternate embodiments, PCV valve 78 may be an electronically controlled valve (e.g., a powertrain control module (PCM) controlled valve) wherein a controller 166 of control system 160 may command a signal to change a position of the valve from an open position (or a position of high flow) to a closed position (or a position of low flow), or vice versa, or any position there-between.

During boosted conditions (when MAP is greater than BP), gases flow from the crankcase, through oil separator 81 and push-side conduit 74 , and into fresh air intake 12 and eventually into the combustion chamber 34 . This may be done in a stale air manner where no intake manifold air is let into the crankcase 28 or in a positive crankcase ventilation manner where some manifold air is metered into the crankcase 28 . The flow of gases from the crankcase through the push-side conduit 74 , and into intake passage 12 via push-side port 101 is also referred to herein as push-side PCV flow or PCV push-side flow.

The gases in crankcase 28 may include un-burned fuel, un-combusted air, and fully or partially combusted gases. Further, lubricant mist may also be present. As such, various oil separators may be incorporated in positive PCV system 16 to reduce exiting of the oil mist while allowing exiting of fuel vapor from the crankcase 28 through the PCV system 16 . For example, conduit 76 may include a uni-directional oil separator 82 which filters oil from vapors exiting crankcase 28 before they re-enter the intake manifold 42 . Another oil separator 81 may be disposed in crankcase ventilation tube 74 to remove oil from the stream of gases exiting the crankcases during boosted operation. Additionally, in some embodiments, conduit 76 may also include a vacuum sensor 84 coupled to the PCV system 16 .

Exhaust combustion gases exit the combustion chamber 34 via exhaust passage 60 located upstream of turbine 62 . An exhaust gas sensor 64 may be disposed along exhaust passage 60 upstream of turbine 62 . Turbine 62 may be equipped with a wastegate bypassing it (not shown), and turbine 62 may be driven by the flow of exhaust gases passing there through. Furthermore, turbine 62 may be mechanically coupled to compressor 50 via a common shaft (not shown), such that rotation of turbine 62 may drive compressor 50 . Sensor 64 may be a suitable sensor for providing an indication of engine air-to-fuel ratio from exhaust gas constituents. For example, sensor 64 may be a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor. Exhaust gas sensor 64 may be in electrical communication with controller 166 . As discussed herein, the engine air-to-fuel ratio may be utilized to estimate an oil dilution amount.

All or part of the treated exhaust from emission control device 69 may be released into the atmosphere via exhaust conduit 70 . Depending on operating conditions, however, some exhaust may be diverted instead to EGR passage 51 , through EGR cooler 47 and EGR valve 49 , to the inlet of compressor 50 . In this manner, the compressor is configured to admit exhaust tapped from downstream of turbine 62 . The EGR valve may be opened to admit a controlled amount of cooled exhaust gas to the compressor inlet for desirable combustion and emissions-control performance. In this way, engine system 100 is adapted to provide external, low-pressure (LP) EGR. The rotation of the compressor, in addition to the relatively long LP EGR flow path in engine system 100 , provides excellent homogenization of the exhaust gas into the intake air charge. Further, the disposition of EGR take-off and mixing points provides effective cooling of the exhaust gas for increased available EGR mass and improved performance.

In some examples, EGR system 18 may further include a differential pressure over valve (DPOV) sensor (not pictured). In one example, an EGR flow rate may be estimated based on the DPOV system which includes the DPOV sensor that detects a pressure difference between an upstream region of the EGR valve 49 and a downstream region of EGR valve 49 . This EGR flow rate may be used in part to determine the contribution of EGR gases to measurements of intake air oxygen content as measured by IAO2 sensor 88 .

Fuel system 19 may include a fuel tank 128 coupled to a fuel pump system 202 . The fuel pump system 202 may include one or more pumps for pressurizing fuel delivered to the injectors of engine 111 , such as the example direct fuel injector 220 shown. While only a single fuel injector 220 is shown, additional fuel injectors may be provided for each cylinder, for instance port fuel injector 221 at FIG. 2 . It will be appreciated that fuel system 19 may be a return-less fuel system, a return fuel system, or various other types of fuel system. Vapors generated in fuel system 19 may be routed to a fuel vapor canister 104 , described further below, via conduit 135 , before being purged via fuel vapor purging system 17 . Conduit 135 may optionally include a fuel tank isolation valve. Among other functions, fuel tank isolation valve may allow the fuel vapor canister 104 to be maintained at a low pressure or vacuum without increasing the fuel evaporation rate from the tank (which would otherwise occur if the fuel tank pressure were lowered). The fuel tank 128 may hold a plurality of fuel blends, including fuel with a range of alcohol concentrations, such as various gasoline-ethanol blends, including E10, E85, gasoline, etc., and combinations thereof.

Fuel vapor canister 104 may be filled with an appropriate adsorbent and configured to temporarily trap fuel vapors (including vaporized hydrocarbons) during fuel tank refilling operations and “running loss” (that is, fuel vaporized during vehicle operation). In one example, the adsorbent used is activated charcoal. Fuel vapor canister 104 may further include a vent 136 which may route gases out of the canister 104 to the atmosphere when storing, or trapping, fuel vapors from fuel system 19 . Vent 136 may also allow fresh air to be drawn into fuel vapor canister 104 when purging stored fuel vapors from fuel system 19 to intake 12 via fuel vapor purging system 17 . While this example shows vent 136 communicating with fresh, unheated air, various modifications may also be used. Flow of air and vapors between fuel vapor canister 104 and the atmosphere may be regulated by the operation of a canister vent solenoid (not shown), coupled to canister vent valve 172 .

Fuel vapor canister 104 operates to store vaporized hydrocarbons (HCs) from fuel system 19 . Under some operating conditions, such as during refueling, fuel vapors present in the fuel tank may be displaced when liquid is added to the tank. The displaced air and/or fuel vapors may be routed from the fuel tank 128 to the fuel vapor canister 104 , and then to the atmosphere through vent 136 . In this way, an increased amount of vaporized HCs may be stored in fuel vapor canister 104 .

During a later engine operation, the stored vapors may be released back into the incoming air charge via fuel vapor purging system 17 . Fuel vapor purging system 17 includes ejector 140 , which includes a housing 168 . One or more check valves may be arranged within housing 168 . Further, ejector 140 includes a first port 142 , a second port 144 , and a third port 146 . In one example, only these three ports are included. Duct 148 couples first port 142 of ejector 140 to intake passage 12 downstream of each of compressor 50 and throttle 44 . Duct 150 couples second port 144 of ejector 140 to fuel vapor canister 104 . Duct 152 couples third port 146 of ejector 140 to intake passage 12 upstream of compressor 50 (i.e., at an upstream inlet of the compressor). Duct 152 may be coupled to intake passage 12 downstream of an air filter 54 . A CPV 158 is arranged in duct 150 , to regulate the flow of vapors from fuel vapor canister 104 to ejector 140 . Optionally, a third check valve 170 may be included in duct 148 intermediate the ejector and the intake passage. The ejector is designed such that during boost conditions, a low pressure zone is created in the ejector which draws fuel vapors from the CPV to the upstream inlet of the compressor. Under vacuum conditions, for example when intake manifold vacuum is present, fuel vapors are drawn from the CPV, through the ejector, to the intake manifold.

The description continues in the full USPTO document.